1. Field of the Invention
This invention relates to an indicator, and more particularly to an indicator such as a speedmeter or tachometer used in motor vehicles, which has an ultraviolet lamp for illuminating indicia, such as scales and numerals arranged on a scale plate of the indicator, containing fluorescent brightener therein and a pointer on which fluorescent brightener is applied for visibility improvement.
2. Description of the Prior Art
One type of prior art indicators, such as a speed meter or tachometer for use in motor vehicles, includes an ultraviolet lamp for illuminating indicia, such as scales or numerals, that contain fluorescent brightener therein, and a pointer on which fluorescent brightener is applied for indicating a specific value in cooperation with the indicia. In such a conventional indicator, the fluorescent brightener fluoresce when the indicia and the pointer receive ultraviolet light from the ultraviolet lamp. Therefore, the luminance of the indicia and pointer becomes good when the ultraviolet lamp is turned on, which makes the indicia and pointer especially visible at night.
However, in the conventional indicator, the fluorescent brightener is simply added directly to the indicia on the scale plate or simply applied onto an upper surface of the pointer. Namely, according to the conventional indicator, as shown in FIG. 1, fluorescent brightner 1 is applied onto a whole upper surface of a pointer 2. Further, as shown in FIG. 2, indicia 3 such as scales and numerals are printed on a scale plate 4 by an ink 5 having a different color from a ground color of the scale plate 4 and containing fluorescent brightener therein. Therefore, there is a problem that the pointer 2 and indicia 3 are too bright and distracting for a driver when illuminated by the ultraviolet lamp. As a result, the driver's night-time visibility and concentration may be dangerously impaired. This means that the sizes of the indicia and the upper surface of the pointer, although they give good visibility for a driver under day-light, are too large if fluorescent brightener is simply applied thereto and then an ultraviolet light is illuminated therefor under darkness.